Atomic layer etching of tungsten for enhanced tungsten deposition fill

Abstract

Methods of depositing tungsten into high aspect ratio features using a dep-etch-dep process integrating various deposition techniques with alternating pulses of surface modification and removal during etch are provided herein.

What is claimed is: 
     
         1 . A method of filling a feature disposed in a substrate, the method comprising:
 (a) etching a first metal within a feature to remove a first portion of the first metal at a top of the feature in a first process chamber to form an exposed surface of the first metal; and   (b) selectively depositing a second metal atop the exposed surface of the first metal within the feature to a predetermined thickness in a second process chamber, wherein etching the first metal and selectively depositing the second metal are performed without oxygen contacting the exposed surface.   
     
     
         2 . The method of  claim 1 , wherein the first metal is cobalt and the second metal is tungsten. 
     
     
         3 . The method of  claim 1 , wherein (a) is performed using atomic layer etch (ALE). 
     
     
         4 . The method of  claim 3 , wherein etching the first metal using ALE comprises exposing the feature to a halogen-containing gas to form a modified surface of the first metal, and exposing the modified surface to an activation gas to remove the first portion of the first metal at the top of the feature. 
     
     
         5 . The method of  claim 1 , wherein (b) is performed subsequent to (a) within a cluster tool under continuous vacuum. 
     
     
         6 . The method of  claim 1 , wherein the first metal is tungsten and the second metal is molybdenum. 
     
     
         7 . A method of filling a feature disposed in a substrate, the method comprising:
 (a) depositing a first metal within a feature to a first predetermined thickness in a first process chamber;   (b) etching the first metal to remove a first portion of the first metal at a top of the feature in a second process chamber different than the first process chamber to form an exposed surface of the first metal; and   (c) selectively depositing a second metal atop the exposed surface of the first metal within the feature to a second predetermined thickness in a third process chamber, wherein etching the first metal and selectively depositing the second metal are performed without oxygen contacting the exposed surface.   
     
     
         8 . The method of  claim 7 , wherein (a) and (c) are performed using chemical vapor deposition and (b) is performed using atomic layer etch (ALE). 
     
     
         9 . The method of  claim 8 , wherein etching the first metal using ALE comprises exposing the feature to a halogen-containing gas to form a modified surface of the first metal, and exposing the modified surface to an activation gas to remove the first portion of the first metal at the top of the feature. 
     
     
         10 . The method of  claim 7 , wherein the first metal is cobalt and the second metal is tungsten. 
     
     
         11 . The method of  claim 7 , wherein the first metal is tungsten and the second metal is molybdenum. 
     
     
         12 . The method of  claim 7 , wherein (c) is performed subsequent to (b) within a cluster tool under continuous vacuum. 
     
     
         13 . A cluster tool, comprising:
 a first transfer chamber;   an atomic layer etching (ALE) chamber coupled to the first transfer chamber, wherein the atomic layer etching chamber is configured to etch a first metal within a feature of a substrate to remove a first portion of the first metal at a top of the feature in the atomic layer etching chamber to form an exposed surface of the first metal; a chemical vapor deposition (CVD) chamber configured to selectively deposit a second metal atop the exposed surface of the first metal within the feature to a predetermined thickness in the chemical vapor deposition chamber, wherein the cluster tool is configured to transfer from the atomic layer etching chamber to the chemical vapor deposition chamber under continuous vacuum, and wherein the first metal is cobalt and the second metal is tungsten.   
     
     
         14 . The cluster tool of  claim 13 , wherein the cluster tool is configured to transfer from the atomic layer etching chamber to the chemical vapor deposition chamber without oxygen. 
     
     
         15 . The cluster tool of  claim 13 , further comprising at least one pre-clean chamber coupled to the first transfer chamber.